194' Annals Entomological Society of America [Vol. ^CIl/ 



By far the greatest part of the work was done on P. cynthia, 

 since it was most readily available. 5. cecropia offered the best ' 

 material to follow out morphological changes — being the largest 

 form. Material was procured at Ithaca and New York City. ^ 



For various ends, various technique was used. The material ■■' 

 f6r spermatogenesis Was killed and fixed in Benda's fluid,/ 

 Zerikers, Gilson's of -Herman's mixtures. Pereyni's reagent' 

 was' found to be very good for synaptic stages of mitosis. A 

 new mixture, formulated as follows, fixed "ring" stages bettefl 

 than any of the more common solutions: ■■ 



2% copper sulphate 3 parts 



2% platinum chlorid 2 parts 



Acetic acid 6-10 drops to every 100 c. c. ' 



Water (distilled) .: I :.' j .(....'... 1, .,..,... 10 parts 



This solution is strictly a nuclear fixer. For the study of 

 the tissues other than the germ cells, Gilson's or Herman's 

 mixtures were employed. 



Of the stains, Weigert's copper haemotoxylin was found 

 best, this staining cytoplasm with as much exactness as the 

 nucleoplasm. Mallory's connective tissue stain was indis- 

 pensable for the muscular and fibrous coats of the various 

 organs, especially the coats of the testis. Delafield's haemo- 

 toxylin counterstained with picro-fuchsin was found to be very 

 good for determining the presence of a cuticula covering. 



In making dissections, especially during the larval and early 

 pupal periods, when the organs of the genital system are very 

 delicate and very difficult to see, the preparations were lightly 

 stained with Delafield's haernotoxylin, the stain being dropped 

 on the dissection after the water had been poured out of the 

 pan. In preparations made in this way, the finer organs like 

 the vasa deferentia, ligaments, and nerves, could be followed 

 along their course. These structures stain deeply, while the 

 fat lobules do not. 



In order to make a more detailed study of the nerves invest- 

 ing the caudal portion of the abdomen, specimens were injected 

 with 1% Griibler's "B-X" methylene blue in a .9% salt solution'' 

 and allowed to remain so treated, in a living condition for from;'; 

 twelve to twenty-four hours. The earlier stages were found to'/ 

 take up the stain more readily than the adults. In adults \ 

 thirty-six hours were required to have this intra vitani methodx 

 take effect. —^ -"! 



